Generation of an ultra-superheated steam composition and gasification therewith

ABSTRACT

A method for gasifying carbonaceous materials to fuel gases comprises the formation of an ultra-superheated steam (USS) composition substantially containing water vapor, carbon dioxide and highly reactive free radicals thereof, at a temperature of about 2400° F. (1316° C.) to about 5000° F. (2760° C.). Rapid gasification of a carbonaceous material with USS is indicated by the production of USS in a clear, colorless flame, and its enthalpy obviates the need for super-stoichiometric steam input. In a related aspect of the invention, gasification output per pound of steam as well as CO and H 2  concentrations are increased by adding a relatively small amount of an oxygen-containing material such as cellulose to the input elemental carbon material, or by adding a relatively small amount of elemental carbon material such as coal to an input oxygen-containing material such as cellulose. Methods for controlling a gasifier system to enhance gasification efficiency are described.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to gasification of carbonaceousmaterials to useful fuel gases and other products. More particularly,the invention pertains to improvements in generating a highly reactivegasifying agent and customization of carbonaceous compositions, and usesthereof in thermal gasification processes.

[0003] 2. State of the Art

[0004] Thermal gasification using superheated steam is a well-known art.In a typical thermal gasification process, a carbonaceous material suchas coal or cellulosic waste material is reacted with steam or a hot gasat temperatures greater than about 1400° F. (760° C.), to produce acombustible fuel gas largely composed of carbon monoxide (CO) andhydrogen (H₂). Carbon dioxide (CO₂) and water vapor (H₂O) are generallypresent in substantial quantities. Methanation, which increasesexponentially with pressure and decreases with reactor temperature, alsooccurs to produce hydrocarbons e.g. methane. Small amounts of othergases such as ethane and ethylene may also be produced. The gasificationconditions are controlled to yield a product gas for use as a fuel or asa feedstock for making other hydrocarbon fuels, ammonia, methanol,hydrazine, et. cetera.

[0005] The well-known chemical reactions which occur in thermalgasification of carbonaceous materials include the following endothermicequations:

C+H₂O

H₂+CO −56,520 BTU/lb. mole carbon  (1)

C+2H₂O

2H₂+CO₂ −38,830 BTU/lb. mole carbon  (2)

[0006] The actual composition of the product gas is influenced by manyfactors, including the quantities and composition of incoming feedmaterials, gasification temperature, pressure, and reactor residencetime.

[0007] Thus, starting with a set of chemical component input andgasification conditions, the actual composition of the product gas iscalculated by consideration of reaction rates, chemical equilibrium,mass balances, and thermal balances. In some systems, catalysts areutilized to change the reaction rates and shift the product gascomposition.

[0008] A major concern in developing workable processes for gasifyingmaterials such as coal and biosolids is the high thermal energyrequirement for driving the endothermic reactions.

[0009] In most gasification processes, substantial heat must be providedto satisfy the highly endothermic chemical reactions. This heat istypically provided by either (a) partially combusting the incomingcarbonaceous material, (b) exothermically reacting a material such ascalcined lime with carbon dioxide, and/or (c) by providing heat from anoutside source, e.g. hot char circulation, addition of excess steam,etc.

[0010] In some gasification systems, mixtures of air and steam are usedas the gasifying agent, and some of the required heat is provided byoxidation of a portion of the carbonaceous material. In such systems,heating of the inert nitrogen gas in the air wastes energy, and theproduced gas will contain a substantial fraction of free nitrogen,resulting in a low heating value.

[0011] Gasification with a mixture of steam and pure oxygen has beenpromoted, but full development has been hindered by (a) the high cost ofoxygen, (b) combustion of a large portion of the carbonaceous materialto non-fuels (CO₂ and water), and (c) a resulting product gas containinga low ratio of hydrogen gas to the total of carbon dioxide and carbonmonoxide. The primary industrial need is for gases with higher H₂:COratios.

[0012] Steam-only gasification has been investigated and usedcommercially since about 1950-1960. It is usually desirable to maintaina steam:carbon ratio which is close to a value at which the carbon isfully reacted by reactions (1) and (2) above, with minimal excess steam.More particularly, the conversion of carbon to CO should be maximized,as in reaction (1). Thus, an extraneous heat source is usually providedto supply the necessary heating requirements. The product gas typicallyhas a higher H₂:CO ratio than when gasifying with a mixture of steam andair or oxygen. However, because of the limited heat in the steam, theproblems associated with steam-only gasification include low achievablereaction temperatures i.e. typically less than about 1500° F. (815° C.),where long residence times and high energy consumption prevail. Tooperate at higher temperatures, complex heat transfer systems areutilized in order to avoid intermingling of combustion gases with thegasification products. Such systems entail high capital and operatingcosts, and are generally considered to be uneconomic.

[0013] In U.S. Pat. No. 4,004,896 of Soo, it is proposed to operate athermal gasification system with a large quantity of excess steam, i.e.2-10 times that required for full gasification of the carbon. In Soo,the thermal requirements of gasification are provided by copiousquantities of steam. However, the quantities of H₂ and CO produced perpound of steam are low.

[0014] The use of high temperature superheated steam for gasificationprocesses has been proposed. In a system configuration described inEmerging Technology Bulletin No. EPA/540/F-93/XXX entitled SPOUTED BEDREACTOR, dated August 1993, by the U.S. Environmental Protection Agency,streams of methane and pure oxygen are fed to a burner, with the hotflame injected into a stream of low temperature steam which is passedinto a primary gasification reactor. The gasification temperature ispartially maintained by oxidation of portions of the feed material andgases leaving the reactor. The injected steam supplies only a portion ofthe heat required to maintain the low gasification temperature.

[0015] U.S. Pat. No. 3,959,401 of Albright et al. describes an apparatusfor cracking gaseous and liquid hydrocarbon fieedstocks to otherchemicals, using a hot gas. It is stated that a hot gas temperature upto 3000° C. (5432° F.) may be used. The source of the hot gas and itscomposition is not indicated. Furthermore, the sole purpose of the hotgas is to supply heat for the endothermic cracking reactions. The hotgas does not react to become part of the product. The purpose of theapparatus is cracking, and gasification of carbonaceous materials to COand H₂ is not in view.

[0016] In U.S. Pat. No. 4,013,428 of Babbitt, an oxygen blown system forgasifying powdered coal is described. A fuel is pre-burned with oxygento form a mixture of steam and CO₂ to which a small amount of water isadded. The combustion temperature is indicated to be about 4722° F., andthe gas is contacted with the powdered coal to produce a product gas.Each of fuel, oxygen and steam is separately introduced into thepre-burner.

[0017] Babbitt also describes a process in which the pre-burner is fedseparate streams of fuel, air and steam, creating a gasifying agentcontaining CO₂, steam and inert nitrogen at a temperature of about 3770°F. The presence of nitrogen is detrimental to energy efficiency andresults in a product gas of lower heating value.

BRIEF SUMMARY OF THE INVENTION

[0018] A primary object of the present invention is to provide agasification process for gasifying a carbonaceous material such that amaximum quantity of usable product gas is obtained per unit of steamintroduced into the gasifier reactor.

[0019] Another object of the invention is to provide a thermalgasification process in which a maximum quantity of usable product gasis obtained per unit of oxygen burned in a pre-burner, in order tooperate at lower cost.

[0020] A further object of the invention is to provide a thermalgasification process in which both water vapor and carbon dioxide in theproduct gas are substantially reduced.

[0021] Another object of the invention is to provide a gasificationprocess in which the gasification rate at temperatures of about 1200° F.(649° C.) to about 2200° F. (1204° C.) is significantly increased.

[0022] An additional object of the present invention is to provide agasification process in which the gasifying agent is a high energyultra-superheated steam composition substantially free of oxygen andnitrogen, and contains a high concentration of dissociation freeradicals.

[0023] A further object of the invention is to provide a gasificationprocess wherein all or nearly all of the heat requirement is supplied bythe gasifying agent.

[0024] Another object of the invention is to provide methods formaximizing the concentrations of CO and H₂ in the product gas.

[0025] An additional object of the invention is to provide methods forcontrolling a gasification system at conditions optimal with respect toraw material consumption, yield, and cost.

[0026] Other objects and considerations of the invention will becomeapparent in the description of the invention when taken in conjunctionwith the attached drawings.

[0027] In accordance with the invention, it has been discovered that ahighly reactive composition of steam may be formed under certainconditions. This composition is denoted herein as ultra-superheatedsteam, abbreviated as USS, and is indicated as providing significantadvantages as a gasifying agent in thermal gasification of carbonaceousmaterials including elemental carbon, hydrocarbons, cellulose, etc.

[0028] In its most reactive or “pure” form, ultra-superheated steamcomprises a mixture of water vapor and carbon dioxide, together with anenhanced population of free radicals of the combustion products, and isformed under such conditions that it is substantially devoid of freeoxygen and free nitrogen. Moreover, the temperature of USS is defined asbeing significantly greater than steam produced in even the mostadvanced existing steam generating power plants, i.e. greater than about2400° F. (1316° C.). As described herein, USS may be produced attemperatures ranging from about 2400° F. (1316° C.) to about 5000° F.(2760° C.).

[0029] In order to produce USS, a substantially ash-free carbonaceousfuel such as fuel oil, natural gas, etc. is burned by a homogeneousmixture of oxygen and water vapor at or very near to stoichiometricfuel:oxygen conditions. It has been found that the oxygen and watervapor must be homogeneously mixed prior to contact with the fuel. Inpractice, either the oxygen or water vapor, or the mixture thereof, maybe preheated depending upon the heating value of the fuel and systemparameters.

[0030] It has been discovered that when the stoichiometric combustion isconducted in a high-turbulence burner such as one having an aerodynamicor bluff body flame holder, at an adiabatic stable flame temperature ofabout 2400° F. (1316° C.) to about 5000° F. (2760° C.), a USScomposition is produced as a distinctive clear, colorless flameindicative of a high concentration of free radicals. These free radicalsare known to generally enhance reaction rates and reaction completion.

[0031] In another aspect of the invention, it has been discovered thatthe chemical and thermodynamic efficiencies of gasification may besignificantly increased by gasifying certain mixtures of a carbonaceousmaterial containing little or no oxygen with a carbonaceous materialcontaining oxygen. This gain of CO and H₂ may occur at both ends of thecomposition spectrum. For example, supplementing an a-cellulose materialwith up to about 30-40 w/w % elemental carbon, or supplementing anelemental carbon material with up to about 5-8 w/w % a-cellulosicmaterial enhances burnable gas production per unit of oxygen consumed.Moreover, the “cold efficiency” of the process, defined as the chemicalheat in the product gas divided by the toal heat input, is increased byreducing the CO₂ and free water vapor. The heating value of the producedgas is increased by reducing the CO₂. Although a similar heating valueincrease is achieved by the reduction of H₂O, the product gas isgenerally dried prior to use. An optimal ratio of carbon and cellulosicmaterial may be maintained by controlling the feed material ratio tomaintain a CO₂ or water content of the gasification reactor outlet gasat a low value approaching zero. Use of a mixed feed material permitscontrol of a gasification process to produce a particular composition ofproduct gas.

[0032] The utilization of each of these aspects in combination resultsin a very rapid gasification with low oxygen consumption, low steamconsumption, and a high heating value product gas, e.g. “syngas”.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is illustrated in the following figures, wherein:

[0034]FIG. 1 is a generalized block diagram of a gasification process inaccordance with the invention;

[0035]FIG. 2 is a general cross-sectional side view of a high turbulenceburner which is representative of burners useful in the practice of theinvention;

[0036]FIG. 3 is a graphical depiction of produced gas composition at2000° F. for gasification by 4000° F. ultra-superheated steam ofelemental carbon supplemented with pure a-cellulose in accordance withthe invention;

[0037]FIG. 4 is a graphical depiction of the net chemical heat outputper pound of burner oxygen consumed to produce a 4000° F.ultra-superheated steam in a 2000° F. gasification process in whichelemental carbon is supplemented with pure a-cellulose in accordancewith the invention;

[0038]FIG. 5 is a graphical depiction of produced gas composition at2000° F. for gasification by 4000° F. ultra-superheated steam of purea-cellulose supplemented with elemental carbon in accordance with theinvention;

[0039]FIG. 6 is a graphical depiction of the net chemical heat outputper pound of burner oxygen consumed to produce a 4000° F.ultra-superheated steam in a 2000° F. gasification process in which pureα-cellulose is supplemented with elemental carbon in accordance with theinvention;

[0040]FIG. 7 is a graphical depiction of produced gas composition at2000° F. for gasification by 3000° F. ultra-superheated steam of anelemental carbon material supplemented with pure a-cellulose inaccordance with the invention;

[0041]FIG. 8 is a graphical depiction of the net chemical heat outputper pound of burner oxygen consumed to produce a 3000° F.ultra-superheated steam in a 2000° F. gasification process in which anelemental carbon material is supplemented with pure α-cellulose inaccordance with the invention; and

[0042]FIG. 9 is a generalized diagram of an exemplary gasificationsystem for illustrating the practice of various aspects of theinvention.

[0043] DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] In this discussion, the term “ultra-superheated steam” or simply“USS” denotes a “synthetic” steam mixture whose composition issubstantially water vapor (H₂O) and carbon dioxide (CO₂), together witha high concentration of their free radical dissociation products. Asdefined herein, pure USS is substantially devoid of oxygen (O₂) andcontains little or no nitrogen gas. It is difficult to produce USS whichhas absolutely no trace of nitrogen or oxygen, and such is not generallyneeded for most gasification applications. Thus, in the methods of theinvention, the term USS refers to a steam composition which may containup to about 3.0 molar percent oxygen and/or up to about 10.0 molarpercent nitrogen.

[0045] For the purposes of this invention, USS is produced at a minimumtemperature of about 2400° F. (1,316° C., 1589° K.), but may have atemperature up to about 5000° F. (2760° C.). Under the conditions atwhich USS is formed, the equilibrium between CO and CO₂ highly favorsCO₂.

[0046] In accordance with this invention, USS is produced by combiningthe following conditions:

[0047] (1) An “artificial air” is formed by combining an enhanced oxygengas and water vapor. The oxygen content of the enhanced oxygen gas is atleast about 80 molar percent, and preferably at least about 90 molarpercent, and the artificial air may have an oxygen content of betweenabout 15 molar percent and about 40 molar percent.

[0048] (2) A substantially ash-free fuel such as methane, natural gas,fuel oil, etc. is burned with the “artificial air”.

[0049] (3) The oxygen provided by the “artificial air” is controlled tobe essentially stoichiometric with respect to the ash-free fuel, so thatvery little free oxygen remains upon combustion.

[0050] (4) The oxygen and water vapor of the “artificial air” must bewell mixed prior to contact with the fuel in a burner.

[0051] (5) The combustion of fuel with the artificial air takes place ina high turbulence burner with an aerodynamic or bluff body flame holderat an adiabatic flame temperature of about 2400° F. (1316° C.) to about5000° F. (2760° C.).

[0052] Production of ultra-superheated steam at these high flametemperatures is characterized by a clear colorless “flame” in the burnerflame holder, complete oxidation of the fuel, and a complete absence ofsoot. Clear colorless flames are characteristic of the generation oflarge quantities of dissociation products, i.e. high energy freeradicals. When an oxygen-free USS is injected into a gasificationreactor, no exothermic reactions will occur outside of the flameenvelope.

[0053] Before proceeding further, it is necessary to define severalterms used in this description. The term “substantially ash-free” refersto a fuel such as commercially available natural gas, propane, fuel oil,etc.

[0054] The term “carbonaceous” will be used herein to define a fuel orgasifiable material which contains elemental carbon, carbohydrate orhydrocarbon materials. Such materials may occur naturally or may beman-made, and may be solid, liquid or gas at ambient temperatures.Carbonaceous materials which are commonly gasified on a large scaleinclude coal, cellulosic materials (biomass), hydrocarbon fuels and thelike.

[0055] The term “flame temperature” is used herein to denote acalculated temperature of the combustion flame based on thermodynamicconsiderations. Actual accurate measurement of a flame temperature isvery difficult. Thus, a theoretical adiabatic flame temperature isdetermined by calculation, ignoring any heat losses by radiation orother means to the atmosphere. Likewise, energy conversion in formingfree radicals is ignored in the flame temperature calculations, sincethe effect is difficult to quantify.

[0056] The term “chemical heat” will be used to define the heat ofcombustion present in a fuel such as natural gas, coal or product gas(syngas).

[0057] Turning now to FIG. 1, the steps in a gasification method 10using USS 40 are depicted. As shown, an oxygen enriched gas 14containing at least about 80 percent oxygen, and preferably at leastabout 90 percent oxygen, is mixed in pre-mix step 20 with water vapor 18to form an “artificial air” 30. The oxygen may comprise anywhere fromabout 15 mole percent to about 40 mole percent of the artificial air 30.The pre-mixing of the oxygen enriched gas 14 and water vapor 18 isimportant to ensure a uniform blend thereof before introduction into thecombustion step 36. In actual practice, the water vapor 18 may beprovided as low pressure steam. The term “artificial air” was coinedbecause when pure oxygen is bubbled through water at a temperature of200° F. (93.3° C.) at atmospheric pressure, the resulting gas mixture atequilibrium will contain about 21 percent oxygen, similar to air. Thenitrogen content of air is replaced by water vapor to avoid the additionof inerts to the gasifier 44. The “artificial air” 30 may be preheatedin step 22 by heat input 26, and is passed to a combustion step 36 asheated artificial air stream 32 to intimately contact and oxidize asubstantially ash-free fuel 34. Some or all of the heat input 26 may beprovided by heat exchange with the hot product gas 52 from thegasification process 44.

[0058] The formation of a high energy USS composition 40 in combustionstep 36 appears to depend upon an efficient, stable, high turbulentcombustion of the fuel 34 and artificial air 32. There may be many typesof burner constructions which will meet these requirements. Examples ofsuch include burners are those in which the combustion takes placeentirely within the flame stabilization zone 28A within an aerodynamicor bluff body flame holder 28 of the burner 38, a particular example ofwhich is generally depicted in FIG. 2. Use of such burners 38 to provideUSS composition 40 to a gasifier 44 avoids the requirement for expensivecomplex equipment for avoiding the contact of burner oxygen 14 with thegasifier feed material 42, and oxidation thereof.

[0059] Many of the burners 38 which may be used are commerciallyavailable for operation at temperatures up to about 5000° F. (2760° C.)and higher. Examples of such burners 38, without limitation thereto, arethose designed for use with air pre-heated to a temperature ofapproximately 1,300° F. (704° C.) and those designed for use withoxygen-enriched air, i.e. >21% oxygen. Some available burners have aconstruction which inherently mixes the oxidizing gas prior tocombustion.

[0060] Returning to FIG. 1, the combustion step 36 produces anultra-superheated steam 40 at a controllable adiabatic flame temperatureof about 2400° F. (1316° C.) to 5000° F. (2760° C.). As already noted,this USS composition 40 comprises primarily water vapor, carbon dioxideand dissociation products thereof, i.e. free radicals. The free oxygenin the USS composition 40 is very low, e.g. typically less than about 3molar percent. The USS composition 40 may contain a small quantity ofnitrogen gas, depending upon the oxygen purity of the enriched gas 14.

[0061] As shown in FIG. 1, the ultra-superheated steam composition 40may be directed to a gasification process 44, where it comprises thegasifying agent. Given a constant feed rate of carbonaceous feedmaterial 42 to the gasifier 44, the gasification temperature, i.e.temperature of outlet product gas 52, is maintained by controlling boththe temperature and quantity of USS composition 40. The USS compositiontemperature is controlled by varying the ratio of water vapor 18 toeither fuel 34 or oxygen enriched gas 14. The quantity of USScomposition 40 per unit feed material 42 is varied to provide therequired energy for maintaining the desired temperature.

[0062] As is well known, gasification of feed materials 42 such as coal,common waste materials and the like results in formation of inert ash46, which is discharged from the gasification process 44.

[0063] Several advantages of the use of USS composition 40 in thermalgasification process 44 result in part from the substantial exclusion ofoxygen and nitrogen. The endothermic gasification reactions may becontrolled to generate product gases 52 largely containing carbonmonoxide and hydrogen. If the gasifier reaction takes place at highpressure, the equilibrium shifts toward the production of methane orother hydrocarbons. In either case, use of USS composition 40 results invery rapid gasification and complete conversion of the carbonaceous feedmaterial 42. The water vapor and CO₂ are substantially all converted toH₂ and CO, with little CO₂ remaining in the gasifier product gas 52. Thequantity of oxygen 14 required to be consumed in burner 38 is relativelylow, resulting in improvements in gasification efficiency. Thus, thehigh cost of oxygen and complex equipment may be ameliorated in thisprocess which uses much less oxygen, avoids the introduction of inertmaterials, e.g. N₂, achieves very high gasification rates, avoids therequirement for large excess quantities of expensive steam, and usesconventional off-the-shelf apparatus.

[0064] With an ultra-superheated steam composition 40, all of the heatrequired to achieve the desired gasification temperatures may beprovided by the change in sensible enthalpy of the USS, i.e. none of thegasification feed material 42 need be burned. This may be achieved byoperating the combustion process 36 at a high adiabatic flametemperature which is controlled to provide the necessary heat. In actualpractice, a portion of the energy in the product gas 52 is recovered ina superheater and waste heat boiler to heat the incoming artificial air32.

[0065] Furthermore, because of the high (but unquantified) concentrationof highly reactive free radicals in USS compositions 40, the endothermicgasification reactions are believed to be accelerated. Thus, a veryrapid and efficient gasification process results from operation atstoichiometric or near-stoichiometric steam addition, without providingadditional heat by other means.

[0066] Turning now to FIG. 9, an exemplary gasification system 10Aillustrates various aspects of the invention. Gasification reactor 48 isshown with a high turbulence burner 38 having a flame stabilization zone28A in a flame holder 28 (see FIG. 2).

[0067] The burner 38 is fed a substantially ash-free fuel 34 such asmethane, propane, natural gas, gasification product gas or a liquid fuelsuch as fuel oil. A homogeneous mixture of oxygen 14 from oxygen source12 and water vapor 18 from waste heat boiler 16 is heated as artificialair stream 30 by passage through superheater 54. The heated artificialair 32 is injected into burner 38 where it is mixed with fuel 34 andburned under turbulent conditions, creating a ultra-superheated steam(USS) composition 40 having an adiabatic flame temperature of betweenabout 2400° F. (1316° C.) to 5000° F. (2760° C.). In the gasificationreactor 48, a carbonaceous feed material 42 is gasified by the USScomposition 40 at a temperature of about 1200° F. (649° C.) to about2200° F. (1204° C.). The product gas 52 is cooled in superheater 54 andpasses as cooled product gas 56 to waste heat boiler 16 for heatingboiler feed water 58. The heated boiler feed water 58 is typicallyheated to become a saturated steam 18 which is homogeneously mixed withoxygen 14 to become “artificial air” 30.

[0068] In this example, the further cooled product gas 60 is thenscrubbed by a water stream 64 in scrubber 62. The scrubbed cooledproduct gas 68 is then dried in dryer 70. Wastewater streams 66 and 72are shown in the figure. The dry product gas 50 is then available forexport from the system 10A. Optionally, a portion 50A of the dry productgas 50 may comprise a portion or all of the fuel 34 introduced into theburner 38. A portion or all of the recycled portion 50A may comprise wetproduct gas 74. which thus supplies water vapor to the burner 38.

[0069] In another aspect of the invention, depicted in FIGS. 3-8, it hasbeen discovered that the feed material to be gasified may comprise amixture of different materials, and the contribution of each componentmaterial controlled to enhance the overall gasification efficiency. Thecarbonaceous materials which are normally gasified generally fall intotwo classes. The first class is a material whose carbon contentsubstantially comprises elemental carbon, such as coal for example. Thesecond class is a carbonaceous material which contains a substantialpercentage of oxygen, typically molecularly bound. Examples of suchmaterials are cellulose or various hydrocarbons.

[0070] It has been discovered that, for example, a relatively minoraddition of coal having no or little combined oxygen to a cellulosematerial having a relatively large combined oxygen content results in aproduced gas of enhanced CO and H₂, and the yield per unit of oxygenconsumed in the burner may be maximized. Furthermore, yield andcomposition enhancement also occur when a minor amount of cellulosematerial is added to a coal.

[0071] Thus, as shown in FIG. 9, the gasifier feed material 42 maycomprise a low oxygen material 42A such as coal, and anoxygen-containing material 42B such as α-cellulose. A commonly usedchemical formula for α-cellulose is C₆H₁₀O₅, which indicates that itcontains nearly 50 w/w percent oxygen.

[0072] Depending upon the particular type and characteristics of thematerials to be gasified, as well as gasification conditions, it may begeneralized that in one embodiment of the invention, the low oxygencarbonaceous material 42A such as coal may comprise about 5 w/w % toabout 50 w/w % of the total feed material 42.

[0073] In another embodiment, the carbonaceous material 42B containingsubstantial oxygen may comprise about 5 w/w % to about 25 w/w % of thetotal feed material 42.

[0074] The curves of FIGS. 3-8 were developed by simultaneously solvingfor the gas components integrating known equilibria relationships intomass and energy balances. In FIGS. 3,5 and 7, the mole percentage 76,78, 80, 82 and 84, respectively of each gas component CO, CO₂, H₂, H₂Oand CH₄ is plotted as a function of the weight percentage of elementalcarbon 42A or cellulose 42B in the gasifier feed material 42. In FIGS.4, 6 and 8, the net gain in chemical heat, i.e. product gas BTU minusfeed material BTU, times 1000, per pounds of oxygen 14 consumed in theburner 48, is plotted as a function of the feed material composition.

[0075] In FIGS. 3 through 6, the temperatures of the burner 38 andreactor outlet gas 52 are assumed to be 4000° F. and 2000° F.,respectively. In FIGS. 3 and 4, a small quantity of an elemental carbonmaterial 42A, e.g. coal is added to a cellulose material 42B as theinput material 42 to a gasifier 48. As the weight percentage of carbon42A in the mixture 42 increases from zero to about 38 percent, the COcontent 76 and H₂ content 80 of the product gas 52 increases.Simultaneously, the CO₂ 78 content and H₂O content 82 fall to zero.Thus, to operate at the most efficient condition, the produced gas 52may be analyzed for CO₂ or H₂O, and the feed mixture 42 adjusted tocontrol the mole percentage of the particular analyzed gas (CO₂ or H₂O)at a positive value near zero, at 3-5 mole percent for example. FIG. 4shows that the net chemical heat output increases many times over as thecontent of carbon 42A is increased. Thus, for example, the addition ofabout 35 w/w percent carbon 42A to a gasification feed materialcomprising cellulose material 42B increases the net chemical heat perpound of oxygen consumed in the burner by about 800 percent. Moreover,calculations indicate that the CO content 76 and H₂ content 80 in theproduct gas 52 are significantly increased.

[0076] Likewise, a similar phenomenon occurs at the other end of thecomposition spectrum. As depicted in FIGS. 5 and 6, a small quantity ofcellulose material 42B is added to a gasification feed materialcomprising carbon 42A e.g. coal feed material. The indicated peak ofenhanced efficiency is shown to occur at about 7 percent cellulose 42B(93 percent carbon 42A). Thus, gasifier operation may be optimized byoperating with a feed material 42 containing about 6 percent cellulose(94 percent carbon), which results are achieved for example bycontrolling the product gas CO₂ mole percent 78 at about 3-5 percent.

[0077] In either case, the gasifier 48 may be controlled at near-idealconditions by monitoring the produced gas composition produced in thegasification reactor. The fraction of interest which is monitored may beeither the CO₂ fraction or the water vapor fraction. Thecarbon:cellulose composition of the feed material 42 is then controlledto maintain the CO₂ or water vapor content at the reactor outlet at aselected controllable positive value approaching zero, e.g. 1-5%.

[0078] Using USS composition 40 of a higher temperature, the quantity ofUSS used may be decreased while yet supplying the required heat to drivethe gasification reactions.

[0079]FIGS. 7 and 8 are analagous to FIGS. 5 and 6, depicting theproduct gas composition and net chemical heat output when the burnerflame temperature (USS temperature) is reduced to 3000° F. A similarpattern of composition and net heat output are evident, but the CO₂concentration 78 and H₂O concentration 82 drop to zero at a somewhatlower mole concentration (about 90.5%) of carbon 42A in the feedmaterial 42. The net chemical heat output per pound oxygen consumed isgreatly increased by adding 8-9 percent cellulosic material 42B to theelemental carbon material 42A.

[0080] Thus, the gasification process may be controlled to maximize theCO and H₂ content. The production of CH₄ and higher order hydrocarbonsincreases exponentially with pressure and decreasing reactortemperature.

EXAMPLE A

[0081] Experiments in producing USS were conducted using a commerciallyavailable burner produced by North American Manufacturing Company ofCleveland, Ohio. The burner, identified as a model #4425-3, with anominal rating of 350,000 BTU/Hr., has an aerodynamic flame holder forproducing a stable flame under high turbulence conditions. The burnerwas mounted on a test stand in the Enercon Systems factory in Elyria,Ohio, and directed to fire through a hole through the factory wall tothe outside. A sheet metal tube was placed about one foot away from theburner flame to shield the flame from direct sunlight for personalobservation. Additional cooling air was allowed to enter the ductcoaxially to avoid overheating the duct.

[0082] The oxidizing gas fed to the burner was either (1) air, or (2) a“synthetic air” comprising a mixture of oxygen (21% w/w) and steam (79%w/w), and the fuel comprised natural gas having a heating value of about1,000 BTU per cubic foot (7140 Kcal per cubic meter). The oxidizing gaspressure was approximately 1 psig. The water vapor i.e. steam wasgenerated by a very small boiler with manual control of the natural gasflow rate to produce water vapor at about 215° F. (102° C.). The boilerwas operated at less than 10 psig pressure. The burner ignition pilot ofthe boiler was operated with a conventional air/natural gas mixture toavoid unnecessary experimental problems. The quantity of nitrogenintroduced by the pilot air was calculated to be less than about 0.1percent of the high temperature ultra-superheated steam (USS) 52 whichwas produced. The flow rates of oxygen, steam and natural gas flows weremeasured by orifice plates.

[0083] The operating conditions and results were as follows:

[0084] Ambient Air Test

[0085] Air composition: 79 w/w % nitrogen, 21 w/w % oxygen

[0086] Firing Rate: approximately 300,000 BTU/Hr.

[0087] When observed during operation with ambient air as the oxidizinggas, the burner produced a blue flame with yellow and red tinges on theflame tips; this observation is normal for combustion with air. Thecalculated adiabatic flame temperature under these conditions was 3550°F. (1954° C.).

[0088] Artificial Air Test

[0089] Artificial Air Composition:

[0090] 21 w/w % oxygen

[0091] 79 w/w % water vapor

[0092] Firing Rate: Approximately 300,000 BTU/Hr.

[0093] During operation with the “synthetic air”, the flame was observedto be clear and colorless, i.e. invisible. However, the sheet metalducting was very hot i.e. glowing red, and the invisible “flame” wasradiating a great deal of heat. The calculated adiabatic flametemperature under these conditions was 3270° F. (1799° C.). As is wellknown, a clear, colorless flame is indicative of the presence of largenumbers of free radicals which enhance reaction rates.

[0094] Contrary to expectations, the “synthetic air” established andmaintained a stable flame with no problems whatsoever.

EXAMPLE B

[0095] Heat balances and material balances about a thermal gasificationsystem of FIG. 9 were calculated using a computer program forsimultaneously solving for steady state equilibrium conditions with massand energy balances. The assumed operating conditions are:

[0096] The rate of carbonaceous feed material 42 to reactor 48 is set at1.00 ton per hour.

[0097] The mixture of gasifer reactor feed material 42 comprised: w/wPercent lb./hour Heat Value, BTU/pound Elemental Carbon 35.00%  700 lb.14,100 Cellulose 65.00% 1300 lb.  7,500 Total 100.00% 2000 lb. (ave.9,810)

[0098] This mixture was chosen from the curve of FIG. 5, which indicatesimproved performance at this feed mixture 42. Pure elemental carbon andpure cellulose of composition C₆H₁₀O₅ were assumed.

[0099] It was assumed that burner fuel 34 comprises methane of heatingvalue 1000 BTU/cubic foot.

[0100] Pre-mixed and pre-heated artificial air 32 is assumed to be at atemperature of 1200° F. (649° C.), and comprises 79.30 w/w % water vapor18 and 20.70 w/w % oxygen 14. The oxygen 14 is stoichiometric withrespect to burner fuel 34. Artificial Air Steam 18 22.98 moles 413.95lb. Methane 34  3.00 moles  48.10 lb. Oxygen 14  6.00 moles 191.90 lb.Total 31.97 moles 653.94 lb.

[0101] Reactor Pressure: approximately atmospheric

[0102] Gasifying Agent: The burner 38 at the above conditions produces aUSS composition 40 at 4000° F. (2204° C.) comprising the following:Steam portion 28.97 moles 521.98 lb. CO₂  3.00 moles 131.96 lb. Total31.97 moles 653.94 lb.

[0103] Burner Inlet: Heat Input, BTU/Hr. Percent of Total Steam, Heat ofVapor. 433,980 22.61 Steam, Sensible Heat 226,431 11.79

[0104] Oxygen, Sensible Heat 111,014 5.78 Methane, Chemical Heat1,148,380 59.82 Total 1,919,805 100.00

[0105] Burner Outlet: Heat Output, BTU/Hr. Percent of Total Steam, Heatof Vapor. 547,246 28.51 Steam, Sensible Heat 1,217,195 63.40 CO₂,Sensible Heat 155,364 8.09 Total 1,919,805 100.00

[0106] Gasification Outlet Temperature: 2000° F. (1093° C.).

[0107] The material and heat balances for the gasification reactor 48are as follows: Overall Material Balance: Material In Moles PoundsCarbon 80.56 967.49 Hydrogen 88.28 177.98 Oxygen 47.14 1508.47 Total215.98 2653.94

[0108] Material Out Moles Pounds CH₄ 0.47 7.59 CO₂ 8.99 395.57 CO 71.101991.38 H₂O 5.21 93.82 H₂ 82.13 165.57 Total 167.89 2653.94

[0109] The composition of the product gas 52 from the gasificationreactor 48 is as follows: Component Mole % Weight % Dry Basis, mole %CH₄ 0.28 0.29 0.29 O₂ 5.35 14.91 5.52 CO 42.35 75.04 43.70 H₂O 3.10 3.540.00 H₂ 48.92 6.24 50.48 Total 100.00 100.00 100.00

[0110] The heat input to the gasifier reactor 48 is as follows:Component BTU/hour From burner gases  1,919,805 From reacting solids19,620,000 Total 21,539,805

[0111] The heat output from the reactor 48 is as follows: ComponentBTU/hour % of total Chemical Heat in CH₄ 181,246 0.84 Chemical Heat inH₂ 10,116,441 46.97 Chemical Heat in CO 8,656,547 40.19 Heat ofVaporiz., H₂O 98,358 0.46 Sensible Heat in CH₄ 14,015 0.07 Sensible Heatin CO₂ 208,839 0.97 Sensible Heat in CO 1,045,352 4.85 Sensible Heat inH₂O 94,167 0.44 Sensible Heat in H₂ 1,124,839 5.22 Total 21,539,805100.00

[0112] Various indicators of the process efficiencies are as follows:

[0113] (a) Pounds of reacted material 42 per 1000 pounds ofsteam=4831.56.

[0114] (b) Pounds of reacted material 42 per pound of oxygenconsumed=10.422.

[0115] (c) Chemical BTU's generated per pound of oxygen=98,774.

[0116] (d) (Output chemical heat-Input chemical heat)/poundoxygen=92,790.

[0117] (e) Pounds methane used per ton of material 42 gasified=48.10.

[0118] (f) Ratio of chemical heat output to methane input=16.51.

[0119] (g) (Total heat from steam and oxygen)/(heat from methane)=0.67.

[0120] (h) Calculated COLD efficiency=88.00%.

[0121] (i) Calculated High Heating Value (HHV) of produced gas, BTU percubic foot (dry)=307

[0122] (j) Total BTU/hour Chemical Heat=18,954,235.

[0123] (k) Initial Chemical Heat/Final Chemical Heat=6.06 percent.

[0124] (l) (Initial Chemical Heat+Heat of Vaporization)/Final ChemicalHeat=8.35 percent.

[0125] It should be noted that in this analysis, product gas 52 iscooled in superheater 54 from 2000° F. (1093° C.) to 1858° F. (1014°C.), while incoming artificial air 30 is heated to 1200° F. (649° C.).In the waste heat boiler 16, feedwater 58 is heated from 80° F. (27° C.)to become saturated steam at 250° F. (121° C.), while the partiallycooled product gas 56 is cooled from 1858° F. (1014° C.) to 1359.3° F.(737.4° C.).

[0126] The operating cost for this example may be calculated from thefollowing assumed costs: Boiler water  $0.08 per gallon ($1.28/1000lbs.) Methane  10.00 per million BTU Carbon (coal)  40.00 per ton ($1.42per million BTU) Cellulose $20.00 per ton ($1.33 per million BTU)

[0127] Based on these assumptions, the net materials cost for thisgasification example is $2.27 per million BTU in the produced gas. Thebreakdown indicates that the cost of oxygen is reduced in thisgasification process to less than 9 percent of the total: Cost of Boilerwater (steam) 1.56% Cost of Methane 26.71% Cost of Oxygen 8.93% Cost ofCarbon (coal) 32.57% Cost of Cellulose 30.24% Total Materials Cost100.00%

[0128] The several examples of producing and using ultra-superheatedsteam which are shown and described herein are considered to beexemplary only, and the descriptions of operating conditions andapparatus utilized thereon are not to be interpreted as limiting theinvention.

[0129] Thus, it is apparent to those skilled in the art that variouschanges and modifications may be made in the methods and apparatus ofthe invention as disclosed herein without departing from the spirit andscope of the invention as defined in the following claims.

What is claimed is:
 1. A method for gasification of a carbonaceousmaterial to a substantially nitrogen-free product gas, comprising thesteps of: providing a source of oxygen-enriched gas containing less thanabout 20 mole percent nitrogen; providing a source of water vapor;pre-mixing said oxygen-enriched gas and water vapor to form asubstantially homogeneous mixture; contacting said substantiallyhomogeneous mixture with a substantially ash-free carbonaceous fuel atsubstantially stoichiometric ratio in a high turbulence burner havingone of an aerodynamic and a bluff body flame holder to promote theformation of free radical species of the combustion products at anadiabatic flame temperature exceeding about 2400° C. (1316° C.); whereinan ultra-superheated steam (USS) composition is produced comprising amixture of superheated water vapor, carbon dioxide and free radicalswith less than about 3.0 mole percent free oxygen; recovering anddirecting said ultra-superheated steam (USS) composition to agasification reactor wherein a carbonaceous material is reacted withsaid ultra-superheated steam (USS) composition to form a product gas. 2.A method in accordance with claim 1, wherein said oxygen-enriched gascomprises at least about 80 mole percent oxygen.
 3. A method inaccordance with claim 1, wherein the homogeneous mixture of steam andoxygen-enriched gas comprises about 15 to about 40 mole percent oxygen.4. A method in accordance with claim 1, wherein said carbonaceous fuelburned in said burner comprises at least one of a liquid petroleumproduct, gaseous hydrocarbon fuel, and a produced fuel gas.
 5. A methodin accordance with claim 1, wherein said carbonaceous fuel burned insaid burner comprises product gas produced in said gasification reactor.6. A method in accordance with claim 1, wherein the quantity of oxygenin said substantially homogeneous mixture is substantiallystoichiometric with respect to the quantity of substantially ash-freefuel.
 7. A method in accordance with claim 1, wherein at least one ofsaid water vapor and oxygen is pre-heated prior to contact with saidcarbonaceous material.
 8. A method in accordance with claim 1, whereinsaid ultra-superheated steam (USS) composition has a temperature ofabout 2400° F. (1316° C.) to about 5000° F.
 9. A method in accordancewith claim 1, wherein said ultra-superheated steam (USS) is essentiallyclear and colorless.
 10. A method in accordance with claim 1, whereinsaid carbonaceous material is gasified at a reactor temperature of about1200° F. (649° C.) to about 2200° F. (1204° C.).
 11. A method inaccordance with claim 1, wherein said carbonaceous material comprisesone of coal, coke, biomass, liquid petroleum fraction, liquid crackingproduct, gaseous hydrocarbon and a refinery waste material.
 12. A methodin accordance with claim 1, wherein said produced fuel gas issubstantially nitrogen-free.
 13. A method in accordance with claim 1,wherein said carbonaceous material gasified by said ultrasuperheatedsteam comprises a mixture of a first carbonaceous material containingsubstantially no oxygen with a second carbonaceous material containingsubstantial oxygen.
 14. A method in accordance with claim 13, whereinsaid first carbonaceous material comprises less than about 10 w/w %oxygen, and said second carbonaceous material comprises at least about20 w/w % oxygen.
 15. A method in accordance with claim 13, wherein saidquantity of said second carbonaceous material to be mixed with saidfirst carbonaceous material is determined by: (a) initiating andmaintaining gasification in at least one ratio of second carbonaceousmaterial to said first carbonaceous material; (b) determining the carbondioxide content of the outlet gas at each ratio of second carbonaceousmaterial to said first carbonaceous material; (c) comparing eachdetermined carbon dioxide content with a minimum controllable positivepreset value thereof; and (d) iterating steps (a) through (c) withincreasing ratios of said second carbonaceous material to said firstcarbonaceous material until said desired minimum controllable positivepreset value of carbon dioxide content is substantially attained.
 16. Amethod in accordance with claim 15, wherein said ratio of secondcarbonaceous material to said first carbonaceous material is adjusted tomaintain a continuous gasification process at substantially said minimumcontrollable positive preset value of carbon dioxide content in saidproduct gas.
 17. A method in accordance with claim 15, wherein the molepercent of carbon dioxide in said product gas is maintained at a valueless than about 1-10 mole percent.
 18. A method in accordance with claim13, wherein said quantity of said second carbonaceous material to bemixed with said first carbonaceous material is determined by: (a)initiating and maintaining gasification in at least one ratio of secondcarbonaceous material to said first carbonaceous material; (b)determining the free water content of the outlet gas at each ratio ofsecond carbonaceous material to said first carbonaceous material; (c)comparing each determined free water content with a minimum controllablepositive preset value thereof; and (d) iterating steps (a) through (c)with increasing ratios of said second carbonaceous material to saidfirst carbonaceous material until said minimum controllable positivepreset value of free water content is substantially attained.
 19. Amethod in accordance with claim 18, wherein said ratio of secondcarbonaceous material to said first carbonaceous material is adjusted tomaintain a continuous gasification process at substantially said minimumcontrollable positive preset value of free water content in said productgas.
 20. A method in accordance with claim 18, wherein the mole percentof free water in said product gas is maintained at a value less thanabout 1-10 mole percent.
 21. A method in accordance with claim 13,wherein said first carbonaceous material comprises one of coal and ahydrocarbon.
 22. A method in accordance with claim 13, wherein saidsecond carbonaceous material comprises a cellulosic material.
 23. Amethod in accordance with claim 13, wherein the first carbonaceousmaterial comprises coal at about 85 w/w % to about 98 w/w %concentration, and the second carbonaceous material comprises acellulosic material at about 2 w/w percent to about 15 w/w percentconcentration.
 24. A method in accordance with claim 13, wherein thefirst carbonaceous material comprises coal at about 10 w/w % to about 60w/w % concentration, and the second carbonaceous material comprises acellulosic material at about 40 w/w percent to about 90 w/w percentconcentration.
 25. A method for producing an ultra-superheated steamcomposition, comprising the steps of: providing a source ofoxygen-enriched gas; providing a source of water vapor; pre-mixing saidoxygen-enriched gas and water vapor from said sources to form asubstantially homogeneous mixture; and contacting said substantiallyhomogeneous mixture with a substantially ash-free fuel in a highturbulence burner with one of an aerodynamic and bluff body flame holderto promote the formation of free radical species of burner combustionproducts at an adiabatic flame temperature of at least about 2400° F.(1316° C.); whereby an ultra-superheated steam composition is producedin said burner comprising a mixture of superheated water vapor, carbondioxide and free radicals with less than about 3.0 mole percent freeoxygen; wherein said ultra-superheated steam composition has atemperature of at least about 2400° F. (1316° C.).
 26. A method inaccordance with claim 25, wherein said oxygen-enriched gas comprises atleast about 80 mole percent oxygen.
 27. A method in accordance withclaim 25, wherein the homogeneous mixture of steam and oxygen-enrichedgas comprises about 15 to about 40 mole percent oxygen.
 28. A method inaccordance with claim 25, wherein the substantially ash-free fuelcomprises one of a petroleum-based liquid, hydrocarbon containing gas,and a produced fuel gas from a gasification process.
 29. A method inaccordance with claim 25, wherein the quantity of oxygen in saidsubstantially homogeneous mixture is substantially stoichiometric withrespect to the quantity of substantially ash-free fuel.
 30. A method inaccordance with claim 25, wherein at least one of said water vapor andoxygen is pre-heated prior to contacting with said substantiallyash-free fuel.
 31. A method in accordance with claim 25, wherein theultra-superheated steam (USS) is produced at an adiabatic flametemperature of between about 2400° F. (1316° C.) and about 5000° F.(2760° C.).
 32. A method in accordance with claim 25, wherein theultra-superheated steam is produced in a clear colorless flame.
 33. Amethod in accordance with claim 25, wherein said produced fuel gas issubstantially nitrogen-free.
 34. A method in accordance with claim 25,further comprising the step of collecting and directing saidultra-superheated steam (USS) to an industrial process.
 35. A method inaccordance with claim 34, wherein said industrial process comprises agasification process in which a carbonaceous material is converted to afuel gas containing substantially CO and H₂.
 36. A method in accordancewith claim 35, wherein said substantially ash-free fuel comprises aportion of the fuel gas produced by said gasification process.
 37. In agasification apparatus for gasifying a carbonaceous material to aproduct gas with an ultra-superheated steam (USS) composition in areactor, the ultra-superheated steam formed in a high turbulence burnerwith an aerodynamic flame holder at an adiabatic flame temperature ofbetween about 2400° F. (1316° C.) and about 5000° F. (2760° C.) bycombustion of a substantially ash-free fuel with a pre-mixture of oxygenand water vapor; wherein a method for controlling the temperature of thegasification product gas comprises: controlling the ratio of (a) oxygenin said pre-mixture to (b) said carbonaceous fuel fed to the burner at anear-stoichiometric value to limit free oxygen in the ultra-superheatedsteam composition to a value generally less than about 3.0 mole percent;and controlling the rate of oxygen and substantially ash-free fuel insaid pre-mixture, whereby the temperature of said product gas iscontrolled at a preset temperature between about 1200° F. (649° C.) andabout 2200° F. (1204° C.).
 38. In a gasification apparatus for gasifyinga carbonaceous material to a product gas with an ultra-superheated steam(USS) composition in a reactor, the ultra-superheated steam formed in ahigh turbulence burner with an aerodynamic flame holder at a anadiabatic flame temperature of between about 2400° F. (1316° C.) andabout 5000° F. (2760° C.) by combustion of a substantially ash-freecarbonaceous fuel with a pre-mixture of oxygen and water vapor; whereina method for controlling the temperature of the gasification product gascomprises: controlling the ratio of (a) oxygen in said pre-mixture to(b) said carbonaceous fuel fed to the burner at a near-stoichiometricvalue to limit free oxygen in the ultra-superheated steam composition ata value generally less than about 3.0 mole percent; controlling the rateof ultra-superheated steam composition at a substantially constantvalue; and controlling the rate of carbonaceous material fed to saidgasification reactor to control the temperature of said product gas at apreset temperature between about 1200° F. (649° C.) and about 2200° F.(1204° C.).
 39. A method for increasing the efficiency of a thermalgasification of a first carbonaceous material substantially comprisingelemental carbon in a gasification reactor, said method comprising thesteps of: determining a quantity of a second carbonaceous materialcontaining oxygen to be combined with said first carbonaceous materialfor optimal gasification; and combining said determined quantity of saidsecond carbonaceous material with said first carbonaceous material; andgasifying said combined first carbonaceous material and secondcarbonaceous material containing oxygen in said reactor to produce aproduct gas.
 40. A method in accordance with claim 39, wherein saidquantity of said second carbonaceous material to be combined with saidfirst carbonaceous material is determined by: (a) initiating andmaintaining gasification in at least one ratio of second carbonaceousmaterial to said first carbonaceous material to produce a product gas;(b) determining the carbon dioxide content of the reactor outlet gas ateach ratio of said second carbonaceous material to said firstcarbonaceous material; (c) predetermining a desirable controllableminimally positive value of carbon dioxide in said reactor outlet gas;(d) comparing each determined carbon dioxide content with saidpredetermined minimally positive value of carbon dioxide; and (e)iterating steps (a) through (c) with increasing ratios of said secondcarbonaceous material to said first carbonaceous material until saidpredetermined controllable minimally positive value is substantiallyattained.
 41. A method in accordance with claim 40, wherein the desiredquantity of second carbonaceous material added to said firstcarbonaceous material at said predetermined controllable minimallypositive value of carbon dioxide is between about 5 percent and about 25percent by weight.
 42. A method for increasing the efficiency of athermal gasification of a second carbonaceous material containingsubstantial oxygen in a gasification reactor, comprising the steps of:determining a quantity of a first carbonaceous material substantiallycomprising elemental carbon to be combined with said second carbonaceousmaterial for optimal gasification; and gasifying said quantity of secondcarbonaceous material and said first carbonaceous material in saidreactor.
 43. A method in accordance with claim 42, wherein said quantityof first carbonaceous material to be combined with said secondcarbonaceous material is determined by: (a) initiating and maintaininggasification in at least one ratio of first carbonaceous material tosaid second carbonaceous material; (b) determining the carbon dioxidecontent of the reactor outlet gas at each ratio of first carbonaceousmaterial to said second carbonaceous material; (c) predetermining adesirable controllable minimally positive value of carbon dioxide insaid reactor outlet gas; (d) comparing each determined carbon dioxidecontent with said predetermined minimally positive value of carbondioxide; and (e) iterating steps (a) through (c) with increasing ratiosof said first carbonaceous material to said second carbonaceous materialuntil said predetermined controllable minimally positive value issubstantially attained.
 44. A method in accordance with claim 43,wherein the desired quantity of first carbonaceous material added tosaid second carbonaceous material at said predetermined controllableminimally positive value of carbon dioxide is between about 5 percentand about 50 percent by weight.
 45. A method for reducing oxygenconsumption per unit produced fuel gas in an oxygen-blown gasificationprocess gasifying a first carbonaceous material substantially comprisingelemental carbon to a substantially nitrogen-free product gas, saidmethod comprising: adding a second carbonaceous material substantiallycomprising cellulose to said first carbonaceous material at about 5 w/wpercent to about 25 w/w percent thereof; and gasifying the mixture ofelemental carbon and cellulosic material at an elevated temperature. 46.A method for reducing oxygen consumption per unit produced fuel gas inan oxygen-blown gasification process gasifying a first carbonaceousmaterial containing cellulose to a substantially nitrogen-free productgas, said method comprising: adding a second carbonaceous materialsubstantially comprising elemental carbon to said first carbonaceousmaterial at about 5 w/w percent to about 50 w/w percent; and gasifyingthe mixture of elemental carbon and cellulosic material at an elevatedtemperature.